The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful ...running period in 2010–2013, the LHC was routinely storing protons at 3.5–4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An uncontrolled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multistage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the collimation system. The studies include tracking of protons through the fields of more than 5000 magnets in the 27 km LHC ring over hundreds of revolutions, and Monte Carlo simulations of particle-matter interactions both in collimators and machine elements being hit by escaping particles. The simulation results agree typically within a factor 2 with measurements of beam loss distributions from the previous LHC run. Considering the complex simulation, which must account for a very large number of unknown imperfections, and in view of the total losses around the ring spanning over 7 orders of magnitude, we consider this an excellent agreement. Our results give confidence in the simulation tools, which are used also for the design of future accelerators.
Potential benefits of multiscreen and multiple device environments were assessed using three different computing environments. A single factor, within-subject study was conducted with 18 engineering ...students in a laboratory experiment. Three levels for the computing environment factor included one with a desktop computer with a single monitor (control, condition A); one with a desktop with dual monitors, as well as a single tablet computer (condition B); and one with a desktop with a single monitor, as well as two tablet computers (condition C). There was no statistically significant difference in efficiency or workload when completing scenarios for the three computing environments. However, a dual monitor desktop with a single tablet computer (B) was the ideal computing environment for the information-rich engineering problem given to participants, supported by significantly fewer errors compared to condition C and significantly higher usability ratings compared to conditions A and C. A single desktop monitor with two tablet computers (C) did not provide any advantage compared to a single desktop monitor (A).
A model of superluminal neutrinos Marfatia, D.; Päs, H.; Pakvasa, S. ...
Physics letters. B,
02/2012, Volume:
707, Issue:
5
Journal Article
Peer reviewed
Open access
Motivated by the tentative observation of superluminal neutrinos by the OPERA experiment, we present a model of active-sterile neutrino oscillations in which sterile neutrinos are superluminal and ...active neutrinos appear superluminal by virtue of neutrino mixing. The model demonstrates some interesting possibilities and challenges that apply to a large class of models aiming to explain the OPERA result.
Previous studies have evaluated the effectiveness of high fidelity patient simulators (HFPS) on nursing training. However, a gap exists on the effects of role assignment in multiple-student ...simulation scenarios. This study explored the effects of role assignment on self-efficacy development in baccalaureate-level nursing students. Using a researcher-developed tool, based upon a previously developed and utilized tool to fit the simulation scenario, the effects of role assignment were determined. Role assignment was found to have a significant effect on self-efficacy development. Furthermore, roles that require the participant to be more involved with the simulation scenario yielded more confident scores than roles that did not require the participant to be as involved. With this study, future multi-student simulation scenarios can be adjusted knowing the impact different roles can have on self-efficacy development.
Bi-maximal mixing of three neutrinos Barger, V.; Pakvasa, S.; Weiler, T.J. ...
Physics letters. B,
10/1998, Volume:
437, Issue:
1
Journal Article
Peer reviewed
Open access
We show that if the solar and atmospheric data are both described by maximal vacuum oscillations at the relevant mass scales then there exists a unique mixing matrix for three neutrino flavors. The ...solution necessarily conserves
CP and automatically implies that there is no disappearance of atmospheric
ν
e
, consistent with indications from the Super-Kamiokande experiment. We also investigate the consequences for three-neutrino mixing if the solar and atmospheric oscillations exhibit mixing that is large but not maximal. For non-maximal mixing
ν
e
↔
ν
τ
and
ν
e
↔
ν
μ
oscillations are predicted that may be observable in future long-baseline experiments.
The inability to fully activate the quadriceps femoris muscle voluntarily is known to accompany several different knee-joint pathologies. The extent of a voluntary-activation deficit in patients ...after isolated rupture of the anterior cruciate ligament (ACL), however, has been reported to be small or nonexistent, making it questionable if a voluntary-activation deficit is a relevant factor for these patients at all.
In this study the ability to voluntarily activate the quadriceps femoris muscles was quantified in 22 male patients with arthroscopically-proven isolated ACL ruptures using an established highly sensitive twitch-interpolation technique. Furthermore, the maximal voluntary contraction force of the quadriceps muscle was obtained by isometric knee-joint torque measurements. The results were compared with an age-, gender-, and activity-matched control group.
There was a moderate but significant mean reduction in maximal voluntary activation (VA) in both the injured (VA: 83.9 +/- 2.3%, mean +/- SEM) and uninjured side (VA: 84.7 +/- 2.2%) in comparison with controls (VA: 91.1 +/- 0.8%). However, of the patients the 23% who presented a considerably reduced voluntary-activation of less than 80% were mainly responsible for the significant mean deficit.
The deficit of isometric muscle strength on the injured side compared with that of controls was explained by the voluntary-activation deficit and a true muscle weakness. On the other hand, the diminished muscle strength of the uninjured side was explained sufficiently by the voluntary-activation deficit alone. Considering the bilateral voluntary-activation deficit, functional muscle tests might not be valid when the uninjured extremity serves as reference.
•Informal caregivers of people with dementia have persistent unmet information needs.•We developed a conceptual framework of dementia caregiver information behavior.•Our framework uses a ...process-level, sociotechnical-systems-based perspective.•Our framework guides information product and process design for dementia caregivers.
Informal caregivers of persons living with dementia have significant unmet information needs that, if met, would better equip them to provide effective care. Despite the existence of health information technologies, websites, resources, and organizations dedicated to dementia caregiving, caregivers continue to report unmet information needs. Caregivers’ continued unmet information needs suggest a misalignment between information products, and caregivers’ information behavior—how caregivers generate, acquire, manage, use, communicate, and seek information. Researchers have developed conceptual models for understanding caregivers’ information behavior, but these models are limited in that they are task-oriented, and they assume that caregivers’ information needs will be met if they engage in information behavior. To address these limitations, the present study sought to explore caregivers’ information behavior as a sociotechnical-systems-based process.
We conduced semi-structured interviews with 30 self-identified caregivers to explore their daily experience of caregiving activities, including their information behavior. We applied a process-based conceptual framework that takes into account inputs, processes, outputs, and feedback mechanisms within a sociotechnical system to guide analysis. The process of interest was caregivers’ information behavior as modeled by the information-seeking and communication model (ISCM). We conducted a deductive content analysis guided by the components of the ISCM. We then used team-based affinity diagramming to collapse and categorize the ISCM components into inputs, processes, outputs, and feedback.
We developed a conceptual model to depict caregivers’ information behavior as a sociotechnical-systems-based process of inputs, processes, and outputs that feedback into the system. The conceptual model consisted of three inputs (i.e., information users, information providers, and information products), three information seeking and communication processes (i.e., information access, information interaction, and information assessment and processing), two outputs (i.e., utility and credibility), and feedback.
Building on and addressing the gaps in previous information behavior models, our conceptual framework advances the previous task-level understandings of caregivers’ information behavior into a comprehensive feedback-driven, process-level perspective consisting of context-based inputs, information seeking and communication processes, outputs, and feedback. A sociotechnical-systems-based understanding of caregivers’ information behavior allows for misalignments between information providers and products, and caregivers’ information behavior not only to be illuminated, but systematically addressed.
Fate of the sterile neutrino Barger, V.; Kayser, B.; Learned, J. ...
Physics letters. B,
09/2000, Volume:
489, Issue:
3
Journal Article
Peer reviewed
In light of recent Super-Kamiokande data and global fits that seem to exclude both pure
ν
μ
→
ν
s
oscillations of atmospheric neutrinos and pure
ν
e
→
ν
s
oscillations of solar neutrinos (where
ν
s
...is a sterile neutrino), we reconsider four-neutrino models to explain the LSND, atmospheric, and solar neutrino oscillation indications. We argue that the solar data, with the exception of the
37Cl results, are suggestive of
ν
e
→
ν
s
oscillations that average to a probability of approximately
1
2
. In this interpretation, with two pairs of nearly degenerate mass eigenstates separated by order 1 eV, the day-night asymmetry, seasonal dependence, and energy dependence for
8B neutrinos should be small. Alternatively, we find that four-neutrino models with one mass eigenstate widely separated from the others (and with small sterile mixings to active neutrinos) may now be acceptable in light of recently updated LSND results; the
37Cl data can be accommodated in this model. For each scenario, we present simple four-neutrino mixing matrices that fit the stated criterion and discuss future tests.
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